Writing instrument



FIG. 1 is a front elevational view of a writing instrument showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a right end elevational view thereof;

FIG. 4 is a left end elevational view thereof;

FIG. 5 is a front elevational view of another embodiment of a writing instrument showing my new design;

FIG. 6 is a top plan view thereof;

FIG. 7 is a left end elevational view thereof; and

FIG. 8 is a right end elevational view thereof. 

The ornamental design for a writing instrument, as shown and described. 